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Pyramid Stars

StarDate:

March 25, 2013

The pyramids of Giza have stood for 45 centuries. These monuments to the kings of Egypt were built with the help of the stars. And one of them has a “window” to the stars.

When the pyramids were built, north was marked not by Polaris, today’s North Star, but by Thuban, a star in the sinuous body of Draco, the dragon. The change is caused by a wobble in Earth’s axis, which causes it to point toward different stars over a 26,000-year cycle.

With Thuban as a guide, architects aligned the sides of the pyramids with the cardinal directions with amazing precision.

The largest of the pyramids, built by King Khufu, contains a shaft that aims at Orion’s Belt. The belt moves across the sky, of course, but it passes across that window every day. In ancient Egypt, the stars of Orion represented Osiris, the god of the underworld. Egyptian religion held that a dead king joined Osiris as one of the stars in that part of the sky. So the shaft provided a path from this world to the next.

Orion is in the southwest as night falls, with his three-star belt lined up roughly parallel to the horizon and the constellation’s brightest stars above and below it.

Thuban, not surprisingly, is in the north. It’s not very bright, but under dark skies it’s fairly easy to find because it’s along the line between Polaris and the tip of the handle of the Big Dipper. It’s a star that did its job well - marking directions for one of the wonders of the ancient world.

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